4-4

#include <stdio.h>
int main(void)
{
  int i,m;
  printf("Enter a number:");
  scanf_s("%d",&m);
  for(i=2;i<=m/2;i++)
  if(m%i==0)
  break;
  if(i>m/2&&m!=1)
  printf("%d is a prime number!\n",m);
  else
  printf("No!\n");
  return 0;
}